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0 sufficiently wide, vehicles (including trucks) can cross one direction of SR 132 traffic at a j time. Therefore, this intersection area was analyzed as two separate intersections. ..! The northbound Bird Road left turn onto westbound SR 132 was analyzed using the Highway Capacity Manual ramp junction methodology for the merging maneuver into the through traffic stream. The westbound left-hand acceleration lane allows vehicles to accelerate and merge into the traffic stream rather than to wait for a large gap in the oncoming traffic stream as would be required at a typical unsignalized intersection. Because the ramp junction methodology was developed for freeways, it assumes two lanes of oncoming traffic. To compensate for the single lane provided on westbound SR 132, the through traffic volumes were doubled in the analysis. Basic roadway segments (including freeways) were analyzed based on volume 1 capacity ratios. The segment capacities for this analysis were based on the Highway Capacity Manual. The following roadways segments were analyzed: j • SR 132: Chrisman Road to Bird Road • SR 132: Bird Road to 1-5 SR 132: 1-5 to Koster Road • 1-5: south of 1-580 • 1-5: 1-580 to Vernalis Interchange • 1-5: Vernalis Interchange to SR 132 • 1-5: north of SR 132 • 1-580: north of SR 132 Weaving analyses were performed for the northbound segment of 1-5 between the loop ramps at SR 132. Weaving is defined as the crossing of two or more traffic streams traveling in the same general direction along a significant length of highway, without the aid of traffic control devices. Weaving areas are formed when a merge area is closely followed by a diverge area, or when an on-ramp is closely followed by an off-ramp and the two are joined by an auxiliary lane. The weaving analysis was performed at the request of Caltrans to determine the potential weaving impacts in the 1-5 weaving section. Caltrans was also concerned about the potential for weaving problems on SR 132 between ,¢ Koster Road and the 1-5 northbound on-ramp. This latter weave would only occur if SR 132 were widened similar to the improvements made at Bird Road. Cumulative traffic conditions were developed based on a modified version of the San Joaquin General Pian transportation model. A version of the General Plan model, which incorporated proposed land use changes included in the City of Modesto General Plan Update, was used as the basis for the study of cumulative transportation impacts (at Caltrans' request). The Modesto General Plan Update model showed considerably higher traffic volumes. on SR 132 than shown for the cumulative analysis for the Vernalis Interchange EIR and for other EIRs recently performed in the area. The traffic volume forecasts contained in the Vernalis Interchange EIR for SR 132 were increased by 32 percent to account for projected growth in the City of Modesto through the year 2017. Draft Environmental Impact Report 4-40 ER-96-3